Family history of 1043 propositi with cleft of the lip and/or palate have been accumulated. The data can be sorted by cleft type, sex, syndromes, presence of additional malformations and by sibships that have multiple affected. Medical and family history information with drawn pedigrees are also available on 334 propositi who are longitudinal patients seen on a twice yearly basis. This group also has serial cephalometric radiographs, dental radiographs, dental casts and facial photographs. Collectively, this unique population is one of the largest and most well documented group of cleft propositi. Use of a computer is necessary in order to handle this large volume of family data to assess the relative contribution of genetic and environmental factors in the etiology of orofacial clefts. The proposed research will involve: 1. Propositi in the longitudinal series and their families; 2. Selected "high risk" families whose parents are still in their reproductive years; 3. Close monitoring of the above families of additional children to refine recurrence risk figures; 4. Retroscpective analysis of medical and pregnancy histories to determine any environmental factors involved in clefting; 5. The analysis of all families of propositi to gain a further understanding on the multifactorial nature of human cleft etiology.